Punching devices are known for applications such as paper punching. It is desirable to minimize the force required to operate the punch. This may be accomplished by improving efficiency of the punch system and by increasing the available leverage. In general, a large punch device can provide large capabilities, or equivalently can provide easy operation in regular use. However, for ordinary use, a practical punch device should be compact and have a small footprint to suit an individual or office worker's desktop.
In a manually actuated punch device a user presses a handle. It is desirable to minimize the force required at the handle to cut a hole into a stack of papers. According to one improvement, force may be reduced directly at the pin. Such improvements are among those disclosed in co-pending U.S. patent application Ser. No. 11/215,423, filed Aug. 30, 2005, titled “Hole Punch Element” by Joel S. Marks, whose entire contents are hereby incorporated by reference.
Another solution to reduced actuation force is in the design of operating levers or other movable parts to link the handle to the pin. Generally, a longer handle stroke with an associated longer hand motion provides increased leverage and reduced force. In a common design for a manual punch, the handle is pressed downward toward a tabletop that supports the device. For a comfortable action, the longest possible handle should be used, where the handle length is defined as the distance between a handle hinge and a hand pressing area.
In contrast, a short handle provides a limited handle stroke since, in the extreme, a short handle quickly becomes vertical in an upper position. As a result, a downward pressing action cannot easily actuate a vertically-oriented handle unless the handle is pushed sideways first. A long handle moved to the same upper position to provide the same handle stroke would still be partially horizontal. Thus, the longer handle can readily be pressed downward. Yet the handle cannot be arbitrarily long if a reasonably sized punch device is to be preserved.
Various designs are known to attempt to provide a useful handle stroke. A further advantage of a long handle is the user's hand remains more upon the same part of the handle since there is minimal angle change. A short handle with large angle change causes the user's hand to roll toward the handle hinge on the handle pressing area. This reduces the user's leverage on the handle.
A typical punch device has an elongated body with a horizontal paper slot. A handle hinges about an axis parallel to the length of the punch with the handle being pressed downward near a center of its length. The handle directly presses the tops of the pins. An example of this type of punch is shown in U.S. Pat. No. 5,778,750 (Drzewiecki et al.) in FIGS. 1 and 1A. A further example is shown in U.S. Pat. No. 3,485,130 (Neustadter). With the proportions shown, the Neustadter '130 punch has a longer handle stroke than that of the Drzewiecki '750 punch of FIG. 1A. However, the footprint of the Neustadter '130 punch is larger (to the left in FIG. 2) to provide a support for downward pressing on the distal end of handle 14.
Another example of a typical punch device is shown in U.S. Pat. No. 4,757,733 (Barlow). In FIG. 6, ridge 40 “transmits pressure” to cap 47 atop each pin. Helical spring 45 surrounds the pin.
U.S. Pat. No. 3,714,857 (Stuertz et al.) and U.S. Pat. No. 2,405,150 (Kern) show another type of handle and linkage. A cantilevered bar extends from one end of the device. As with Neustadter '130 above, the base must be extended to be underneath the handle's pressing end. In Stuertz '857, it is clear especially in the plan view of FIG. 1 how large a footprint is needed to accommodate the extended handle.
Another punch design uses a handle that is co-extensive with the body of the punch device. For example, in U.S. Pat. No. 4,166,404 (Almog), a short lever extends from one end toward the center of the hole punch, which punch has a horizontal paper slot. A longer lever extends from a second end over the first lever and to the first end to a distal pressing area. This design is suited only for a two hole punch since there is no means to apply leverage to a center pin.
Still another design with a co-extending handle is shown in U.S. Pat. No. 5,163,350 (Groswith, III et al.). In this design, a parallelogram type linkage provides pressing forces at multiple locations. U.S. Pat. Nos. 5,829,334 and 6,032,566 (Evans et al.) describe a further co-extensive type handle used in a punch. The Evans punch includes a second handle pivoted near the center of the device about a perpendicular axis to that of the conventional handle. The second handle co-extends with the length of the device and provides increased handle stroke. However, the second handle is much shorter than the length of the punch device because of the central pivot location.
In any punch device it is important to maximize efficiency. One reason is that given a level of effort or input force generated by the user on the operating handle, an efficient hole punch can easily cut through more dense and/or a thicker stack of papers or sheet media. Indeed, friction should be reduced throughout the assembly. In most of the conventional designs, the various moving parts encounter substantial sliding friction.